Tesla's home battery doesn't make economic sense for homeowners
The economics just don't make sense.
The noble home battery user wants independence from the grid, but a more sensible approach would be to pair rooftop panels with batteries designed to extend some solar power into the peak evening hours of electricity demand. When the battery is depleted, the homeowner would switch over to grid power. That's an idea that Tesla has been promoting: Save money by modestly extending the benefits of solar power with help from a battery.
The problem is that this kind of energy "load shifting" doesn't save a penny for most U.S. customers, regardless of the cost of the batteries. Blame a policy known as net metering, explained in more detail below. Even in more favorable markets like Germany, the total cost for buying and installing a home battery would have to drop by almost two-thirds before load shifting would be cheaper than running rooftop panels without any batteries, according to analysis by BNEF. Tesla sees Germany and Australia as the biggest initial markets for daily-use batteries.
Even if home battery costs were to go low enough to make them economical with the current status quo, that fact in itself would likely shift the status quo.
This is already beginning to happen as some utility companies allow people with renewable power sources like solar panels to plug those sources into the grid in order to reduce their energy bills.
Another Bloomberg story from back in December reported on a couple who had added solar panels with the assumption they could connect to the grid and reduce their monthly bill to zero, only to be refused once the panels were installed:
Solar installers here estimate that hundreds if not thousands of the state's residents are being put in solar limbo by a virtual moratorium on new connections in many parts of the company's service area. The reason, according to the Hawaiian Electric Co.: so many Hawaiians are stampeding to solar that circuits may become oversaturated, causing voltage spikes, damaging appliances, electronics and even the utility's equipment. The company needs more time to study the matter.
There's a suspicion, however, that it's less about the circuits and more about the economics of the wide adoption of solar over the last few years. If everyone tries to sell their electricity back to the utility companies, there's no one left around to buy it from them. We seem to be quickly approaching the inflection point, where the utility companies are going to need to start fighting solar, rather than encouraging it.